1 The 34-year-old danced her heart out in Beyonce's "Sorry." 2 There may never be a better shirtless cameo than the Spaniard in Shakira's "Gypsy."3 The Dane is no stranger to trying new things, and came out with her own single called "Oxygen."4 The former No. 1 appeared in her then-boyfriend Redfoo's hit "Let's Get Ridiculous."5 The musicians featured both Andy Murray and Novak Djokovic in their song "Autograph."6 The American showed off her singing chops with "I Will Survive" on The Tonight Show Starring Jimmy Fallon.7 Martin Solveig's massive hit "Hello" also has appearances by Djokovic and Mathilde Johansson.8 After retiring, the Belgian showed up on a reality show called The 12 Labors of Justine Henin and sang "Now It's Time."9 The American shared a little free-style rapping with the world.10 Wyclef Jean came out with "Venus (I'm Ready)" in honor of the great American champion.